Apparatus for removing liquid from fourdrinier wire in paper-making



OC- 31 1967 B. JORDANSSON ETAL 3,350,263

APPARATUS FOR REMOVING' LIQUID FROM FOURDRINIER WIRE IN PAPER-MAKING Filed oct. 19, 1964 N .fsk

QW @mi o INVENTORS LARS BHENGT JORDANSSON & PER BORJE WAHLSTROM BY ,f I /nq/d... her ATTORNEYS United States Patent Mekaniska Werkstad, Karlstad, Sweden, a company of Sweden Filed Oct. 19, 1964, Ser. No. 404,851 Claims priority, application Sweden, Oct. 23,y 1963, 11,612/ 63 2 Claims. (Cl. 162-351) The present invention relates to apparatus for removing fluid from iluid bearing material being conveyed to a drying station and, more particularly, to novel and improved iluid removal means in paper making apparatus and the like, including pulp drying machines, board machines, and suction boxes for use in a Fourdrinier section.

A Fourdrinier section, for example, as is well known in the paper making art, usually includes an endless belt type of conveying means, known as a Fourdrinier wire, adapted to run in a continuous loop over a breast roll, a plurality of table rolls, drainage bars, suction boxes, and a couch roll, and passing back again over the breast roll. The various elements of the Fourdrinier section are structurally supported and carried by suitable frames and beams. The endless belt or wire is in the form of a porous wire mesh on which fluid bearing material such as paper pulp is distributed by means of a headbox to the carrying surface of the conveying means by which it is carried to a drying station. While the lluid bearing material is being carried on the endless belt, water is removed by means of the conventional operation of table rolls and drainage bars. Conventional suction boxes are also used to further remove the water from the paper pulp.

The lluid removal or dewatering function of the table rolls and drainage bars is accomplished in a well known manner by the production of a reduced pressure area be` tween the wire and the outgoing nips of the rolls or bars during the operation of the machine. The water removed by the table rolls and drainage bars is collected in suitable troughs or pans positioned under the rolls and bars, and is then drained off in any suitable fashion. Conventional forms of suction boxes extend transversely across the wire or porous conveying means and are connected in a suitable manner to a vacuum source. The water removed through the wire by suction gathers in the bottom of the suction box and is usually drained off by a pipe connected to one end of the suction box.

Conventional table rolls have been found to be comparatively ineffective as a dewatering device due to the fact that the extension of the rolls dewatering zone in the longitudinal direction of the wire is comparatively only a small part of the space that the roll takes up in the section. Due to the reduced pressure area or vacuum that occurs in the outgoing nip between the wire and the table roll, the wire is bent downwardly, creating disturbances at high wire speeds, thereby limiting the operating speed of the Fourdrinier section. Further, it has been found to be very diflicult to adjust and control the dewatering along a wire section employing table rolls.

Various attempts have been made to either completely or partially substitute suction boxes for the conventional table rolls of a Fourdrinier section. 'Ihe dewatering results accomplished by such substitution have not proven to be satisfactory, primarily because of the fact that it has not been possible to obtain an even and stable dewatering action over the entire width of the wire by means of conventional suction boxes. For example, suction boxes placed near the beginning of the wire section following the breast roll must be able to take care of large volumes of water, and it has been found that convendrainage range of the tional suction boxes having a single drainage outlet at one end have been unable to satisfactorily accomplish this function.

These and other disadvantages are overcome, in accordance with the invention, by the utilization of a suction box system in a Fourdrinier section, wherein a plurality of suction boxes or chambers each having a plurality of suction legs or lluid removal conduit means are positioned at different places along suitable parts of the Fourd-rinier wire. The fluid removal conduit means or suction legs are in the form of substantially straight downwardly directed pipes having openings in the bottom of the suction box or chamber uniformly arranged along the entire length of the suction box transversely to the running direction of the wire and extending downwardly into a water trough or pan, located within the loop of the wire and between the main support beams of the wire section to provide a water seal in common for all of the suction legs of the various suction boxes included in the system. The fluid or water level in the trough or pan is maintained above the bottom openings of the suction legs or pipes, which have a length sufcient to permit a rise in lluid level therein in response to the reduced pressure condition created in the suction chamber without the introduction of water from the trough or pan into the chamber.

The water trough or pan lmay serve as part of a fluid reservoir means which also includes an auxiliary iluid containing means or tank in fluid communication with the pan part positioned to the side of the pan and the wire.

For a more complete understanding of the invention, reference may be had to the following detailed description taken in conjunction with the accompanying figures of the drawing, in which:

FIGURE 1 is a side View of a Fourdrinier section of a paper making machine employing lluid removal means, in accordance with the invention; and

FIG. 2 is a cross-sectional view of the Fourdrinier section of FIG. 1, taken through one of the lluid removal means of the invention.

The disclosed exemplary form of the Fourdrinier section includes a conventional headbox 1 for distributing a pulp suspension over a Fourdrinier wire 3. The wire 3 is arranged in the form of an endless belt or closed loop running over a conventional breast roll 5; a plurality of table rolls 7; a plurality of conventional drainage bars 8; a system of suction boxes or chambers 9, each provided with a plurality of substantially straight downwardly directed suction legs or pipes 11 uniformly arranged along the entire length of the suction chamber 9 in a direction transverse to the running direction of the wire 3; a plurality of conventional suction boxes 13 and a couch roll 15. The wire 3 returns over a wire roll 17, tensioning rolls 19, and wire rolls 21 back around and over the breast roll 5.

The wire section is carried by two longitudinal main beams 23 resting on frames 25. A water trough or pan 27 is arranged between the main beams 23, and extends along the greater part of the wire section from the breast roll 5 to the couch roll 15. The width of the water trough or pan 27 corresponds approximately to the transverse width of the wire 3. The trough 27 is provided with a side outlet 29 connected to a water tank positioned to the side of the wire 3 and its supporting beams 23- and frame members 25. A substantially constant water level is maintained in the lluid reservoir means constituted by the trough 27, the side outlet 29 and the water tank and serves as a water seal in common for all of the external suction legs or pipes 11 of the respective suction boxes 9. Further, the water removed through the wire 3 from the pulp suspension by the operation of the table rolls 7 and the drainage bars 8 is also collected in the trough 27 and drained off through the side outlet 29 to the tank. The substantially constant water level in the fluid reservoir means may be maintained at a selected level by means of suitable conventional drainage controls (not shown).

While the trough 27 may be positioned under only certain of the fluid removal means in the section, it may extend substantially the entire distance between the breast roll and the couch roll 15 so as to collect all of the water removed from the iluid bearing material through the wire 3 by the different uid removal devices. On the other hand, it may be desirable in some circumstances to restrict the size and location of the trough 27 to the operational location of the suction boxes or chambers 9 having the straight suction legs or pipes 11.

Each suction chamber 9 is provided with a conduit 31 which is connected to a suitable vacuum source and another conduit 33 connected to a conventional adjustable air supply (not shown), by means of which the required suction effect is obtained.

Thus there is provided in accordance with the invention novel and improved fluid removal means for use in paper making apparatus and the like employing an elongated porous conveying means adapted to carry uid bearing material to a drying station, wherein a uniformly high fluid removal may be obtained across the entire width of the conveying means.

It will be understood by those skilled in the art that the above disclosed embodiment is meant to be merely exemplary and that it is susceptible of modification and variation without departing from the spirit or scope of the invention. Therefore, the invention is not deemed to be limited except as defined in the appended claims.

We claim:

1. In paper making apparatus and the like including an endless porous belt loop having an upper outer surface of predetermined width transverse to the direction of motion to carry liquid bearin-g material and an exposed inner surface, liquid removal means, comprising a plurality of suction chambers each extending transversely across the full width of the belt, each suction chamber having upper openings contiguous with the exposed inner surface of the belt loop and a bottom provided with a plurality of essentially straight downwardlydirected suction pipes uniformly spaced along the entire length of the said bottom transversely to the direction of motion of the belt, means for producing reduced pressure conditions in said suction chambers to facilitate the withdrawal of liquid from the liquid bearing material through the belt, trough means common to all of said suction chambers and positioned beneath said suction chambers and within said belt loop for containing a volume of liquid at a predetermined level, said suction pipes extending from the bottoms of said suction chambers into the liquid in the said trough means below said predetermined level for effecting the removal of liquid from said suction chambers while maintaining said reduced pressure conditions within said suction chambers, the liquid in said trough means constituting a single liquid seal in common for all said suction pipes, and said pipes constituting a plurality of parallel iiow paths, each of minimum length, from the suction chambers to the liquid seal for removal of liquid from the suction chambers.

2. Apparatus as claimed in claim 1, wherein each of said downwardly directed pipes has a length such that rises in liquid level therein in response to said reduced pressure conditions within said suction chambers do not result in the introduction of liquid from said trough means into said suction chambers.

References Cited UNITED STATES PATENTS 2,893,486 7/1959 Marti 162-364 X 3,079,990 3/1963 Taylor et al 162-363 X 3,149,027 9/1964 Mih 162-364 X S. LEON BASHORE, Primary Examiner. 

1. IN PAPER MAKING APPARATUS AND THE LIKE INCLUDING AN ENDLESS POROUS BELT LOOP HAVING AN UPPER OUTER SURFACE OF PREDETERMINED WIDTH TRANSVERSE TO THE DIRECTION OF MOTION TO CARRY LIQUID BEARING MATERIAL AND AN EXPOSED INNER SURFACE, LIQUID REMOVAL MEANS, COMPRISING A PLURALITY OF SUCTION CHAMBERS EACH EXTENDING TRANSVERSELY ACROSS THE FULL WIDTH OF THE BELT, EACH SUCTION CHAMBER HAVING UPPER OPENINGS CONTIGUOUS WITH THE EXPOSED INNER SURFACE OF THE BELT LOOP AND A BOTTOM PROVIDED WITH A PLURALITY OF ESSENTIALLY STRAIGHT DOWNWARDLYDIRECTED SUCTION PIPES UNIFORMLY SPACED ALONG THE ENTIRE LENGTH OF THE SAID BOTTOM TRANSVERSELY TO THE DIRECTION OF MOTION OF THE BELT, MEANS FOR PRODUCING REDUCED PRESSURE CONDITIONS IN SAID SUCTION CHAMBERS TO FACILITATE THE WITHDRAWAL OF LIQUID FROM THE LIQUID BEARING MATERIAL THROUGH THE BELT, TROUGH MEANS COMMON TO ALL OF SAID SUCTION CHAMBERS AND POSITIONED BENEATH SAID SUCTION CHAMBERS AND WITHIN SAID BELT LOOP FOR CONTAINING A VOLUME OF LIQUID AT A PREDETERMINED LEVEL, SAID SUCTION PIPES EXTENDING FROM THE BOTTOMS OF SAID SUCTION CHAMBERS INTO THE LIQUID IN THE SAID TROUGH MEANS BELOW SAID PREDETERMINED LEVEL FOR EFFECTING THE REMOVAL OF LIQUID FROM SAID SUCTION CHAMBERS WHILE MAINTAINING SAID REDUCED PRESSURE CONDITIONS WITHIN SAID SUCTION CHAMBERS, THE LIQUID IN SAID TROUGH MEANS CONSTITUTING A SINGLE LIQUID SEAL IN COMMON FOR ALL SAID SUCTION PIPES, AND SAID PIPES CONSTITUTING A PLURALITY OF PARALLEL FLOW PATHS, EACH OF MINIMUM LENGTH, FORM THE SUCTION CHAMBERS TO THE LIQUID SEAL FOR REMOVAL OF LIQUID FROM THE SUCTION CHAMBERS. 